Fur treating process



Patented June 15, 1948 UNITED STATES PATENT OFFICE FUR TREATING PROCESS William Page, Cranford, N. J.

No Drawing. Application June 22, 1943,

' Serial No. 491,785

2 Claims.

The present invention is concerned with the production of fur which may be readily processed into felt of improved quality.

This application contains subject matter in common with and is a continuation in part of my application Serial No. 443,927, filed May 2-1, 1942, now abandoned, for a Fur treating process. The subject-matter of this application also relates to the inventions described and claimed in United States Patents Nos. 2,225,843 dated December 24, 1940, and No. 2,309,254 dated January 26, 1943. v

The invention especially relates to an improved so-called carroting process by which rabbit, hare, beaver, and similar types of fur are treated with a carroting solution which comprises a mixtureof zinc sulphate, acetic acid, a peroxidizing agent, and a hydrolyzing agent or agents. As a further and integral part of the invention, the process includes subsequent treatment of the carroted fur to reduce thepossibility ofdeleterious decomposition of the fur by the carrot.

It is well known in the art to process animal fur, particularly rabbit, hare, beaver, and similar types of fur, by a carroting process which gener ally comprises treating the fur with a solution of mercuric nitrate and nitric acid. This solution is usually applied to the fur while still on the pelt although it may be applied after removal of the fur from the pelt. The method of application may vary with the individual operator, according to his theory and experience. Whereas the most usual method of application comprises brushing the carroting solution into the fur either manually or by machine, various other methods have been introduced into the art in recent years. Among these other methods spraying, vapor or steam pressure and application byv friction with a neutral substance coated with a concentrated solution are most prominent.

In general commercial practice, the carroting solution is applied by one of the methods outlined above, the carroted skins then being placed in a drying chamber or in a well ventilated place for drying. The temperatures and methods of drying may vary with the individual operator, depending on the type of skin and the felting speed required, it having been generally determined that a higher drying temperature produces a faster felting fur, while a lower drying temperature makes a slower felting fur. In the higher temperature ranges it has been found that decomposition of the fur fibres occurs as a result of the combination of a strong acid and high temperature. This decomposition, or fibre destruction, is found to occur most rapidly when sulphuric acid is employed'as the hydrolyzing agent. Whereas it is generally known that fur carroted with sulphuric acid mixtures produces the tightest felt, the difiiculty in preventing fibre destruc- 2 tion under normal operating conditions has caused those skilled in the art to use other hydrolyzing agents in order to permit ease of operation and to prevent excessive losses. Various inhibitors have also been introduced into carroting solutions containing sulphuric acid and various controlled conditions of temperature and relative humidity have been employed, but up tothe present time no adequate and satisfactory con- .trol has been developed. It is also known in the art (U. S. Pat. No. 2,070,927) that a treatment of the skins in dried condition with ammonia fumes will'to some extent lessen the continuing deterioration of the fur fibres. However, this procedure has been found to be deficient both the possibility of deleterious decomposition or destruction of the fur by the carroting solution, such that the resulting product shall beof-a higher quality than has been heretofore secured and may be readily processed into a smooth, strong, tight felt which will exhibit substantially improved wearing qualities- Other objects are to provide such a method that shall besimple, economical, efiicient and entirely innocuous with respect to the health of the operating personnel; and to obtain other advantages and results as will be brought out by the following description.

I have discovered .a process for carroting fur which includes the utilization of a carroting so- ,lution comprising zinc sulphate, acetic acid, a

peroxidizing agent, and a hydrolyzing agent or agents of the nature of sulphuric acid, such carroting solution being of suflicient concentration to effect commercially satisfactory felting action,

and subsequently controlling the action of said narrating solution by the addition of ammonia vapor'during the drying cycle. The carroted fur produced by my process is extremely stable and may be stored for long periods of time without any substantial deterioration of the fibres occurring. Fur treated by my process may be readily felted, with an exceptionally low loss in weight during the felting operation. Furthermore, the felted product madefrom the fur treated with my composition and by my process is smoothly and tightly interlaced, resulting in the production of. aflmaterial having exceptionally fine natural lustre and'resiliency of the fibres, whichinturn contributes to the appearance and. wearing,

quality.

My process comprises the treatment of the fur,

ences of the particular operator without departing from the scope of the present invention.-

was carefully controlled. It was found that with a full drying load, at an outside temperature of 70 to 80 F., a three-quarter open position of the damper or valve for 25% to 50% of the total drying period and at the terminal portion thereof, gave the most satisfactory results. As a result 7 of'many experiments, I have found that dilute A drying chamber suitable for the effective use of my process may comprise any completelyenclosed room fitted with an outside heated air source. which may be regulated closely and through'theintake-of which the ammonia may be introduced'in such a-manner as to uniformly comeinto contact with the carroted fur.

Lhave-foundasthe result of many experiments that application ofan acid-neutralizing salt or solution-as a separate step after the fur has been carroted and dried, produces extremely variable results which apparently are attributable. to the differing degrees of attack produced by the carroting solution. In other words, smallfib'red or thinly furred skins have undergone an oven-attack of acid, whereas large-fibred or heavily furredskins have not beensufficiently carroted at the time of applying the neutralizing solution. To insure uniformity of results, I have found that the mosteffi'cacious method consists in subjecting the partially. dried skins to a mild neutralizing action by ammonia, before the fur hasbecome dry, such action being aided by the residualmoisture remaining on the fur, which acts as a solventfor the ammonia. When this method is employed, the carroting solution is gradually neutralizedas the fur dries, thus preventing decomposition of the fibres without interfering with the desirable and beneficial efiects of the initial carrotin action. The larger-fibred or more heavily furred skins which retain a pro portion'ately greater'quantity of the carroting solution arethus the last to be affected by the neutralizing action and hence the'carr'oting action' is properly prolonged.

The' volume of ammonia vapor introduced into the drying chamber maybe determined best'by a direct'correlation with the volume or weight of carroting solution applied to the skins beforedrying. I have also found thatth'e rate of flow of the heatedair into the-drying chamber will govern the volume ofamm'onia vapor to be introduced into such flow. Generally, it has been found that a larger volume of ammonia must be introduced into the'heated air flow when such flow is slow, a smallervolume, over the same period of time, when the flow is more rapid.

The drying chamber used in my. experiments provided a drying area to accommodate 1000 to 2000 skins, depending .on the size thereof. Heated air was introduced through evenly spaced ducts in sucha manner as to insure an even dischargeover'each' skin. An exhaust was also provided to insure collection of moisture ladenair at'a rate equivalent to the rate of introductionof heated air above mentioned. At a point outside'the chamber, a container of 26 Beaum ammonium hydroxide wasplac'ed and'provided with a collector hood andipipe fitted with a manually operated damper or valve, such pipe being attached to the'heated air duct. By regulating the damper, or valve, the amount of ammonia evaporating from the ammonium hydroxide container carroting solutions, requiring 1 to 2 hour drying periods, g'ivethe most satisfactory product when the ammonia vapor is introduced in the range of between 30 and 60 minutes before the fur is completely dried. With concentrated carroting solutions, containing less water to act as solvent for the'ammonia, and requiring a drying time of from 15 to 30 minutes, I have found the most satisfactory product resulted when the ammonia vapor was introduced in the range of between 5 and 10 minutes before the fur was completely dry.

In order to further illustrate my invention, the following examples are given which should not be construed as limiting the same in any manner whatsoever.

Example A B G D Per cent Per cent Per cent Per cent Zincsulpliate (ZnSO4) 3 3 8 8 66 B. Sulphuric acid E2804); c. 8 6 22 17 vol. Hydrogen peroxide (H201) l8 19 50 53 28% Acetic acid (GH3CO OH) 8 8 20 22 To determine the efficacy of my invention, first a-quantity of skins was divided into four lots, each of which was treated with one of the above solutions and placed in a drying chamber until such'time as the fur was properly dried. It was found that the periods of time necessary for drying the fur carroted with dilute solutions A and B were respectively and minutes; the times necessary for drying the fur carroted with concentrated solutions C and D were respectively 15 and 18 minutes.

Secondly, similar lots of skins were carroted in an identical manner and placed in the drying chamber under conditions of temperature and air flow corresponding to those employed above. However, toward the end of the drying, ammonia vapor was introduced into the heated air supply ducts as follows:

When dried the skins were removed from the chamber, and the fur was cut from the skins in the usual manner.

Felting tests were then run on a comparative basis in order to determine whether or not the acid neutralization effected by the ammonia had any desirable and beneficial effect on the resultant felt. Fur treated and dried in accordance with the above procedure was also stored for a period long enough to determine the comparative deterioration of the fibres and the effect of such deterioration on the resultant felt.

The tests showed the ammonia treated fur had a greater stability in storage as compared with fur not so treated. The ammonia-treated fur retained its good quality over a 60 day storage period, while the fur not so treated showed evidence of deterioration by increase in the shrinking time, in weight loss and in quality of the resultant felt. Furthermore, the loss of weight in the felting process was substantially reduced when a composition comprising zinc sulphate, acetic acid, hydrogen peroxide and sulphuric acid was employed as a carroting agent in conjunction with subsequent treatment of the carroted fur with ammonia vapor during the drying thereof.

My composition and process is not limited to any theory or mode of operation but may be modified and changed by those skilled in the art without departing from the spirit or scope of the invention; and I desire to claim all novelty insofar as the prior art permits.

What I claim is:

1. A process for the production of fur that may be readily felted wherein the fur is carroted and subsequently dried which comprises, treating fur with a carroting solution comprising zinc sulphate, acetic acid, hydrogen peroxide and sulphuric acid, drying the fur and separately introducing ammonia gas into contact with said fur 6 during the portion of the drying period when the drying of the fur has proceeded from to toward completion.

2. A process for the production of fur that may be readily felted wherein the fur is carroted and subsequently dried which comprises, treating fur with a carroting solution comprising zinc sulphate, acetic acid, hydrogen peroxide and sulphuric acid, drying the fur, evaporating a 26 Beaum solution of ammonium hydroxide to pro duce ammonia gas, separately introducing said ammonia gas with heated air into contact with said fur during the portion of the drying period when the drying of the fur has proceeded from 50% to 75% toward completion, and controlling the evaporation of the ammonium hydroxide so as to regulate both the rate and the quantity of the ammonia released.

WILLIAM PAGE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

